The victim of the attack, which took place at the Skänninge prison in Mjölby in central Sweden, suffered repeated kicks to the head and torso as part of an attempt by fellow inmates to get him to hand over 95,000 kronor ($14,000).
On one occasion, the gang of four prisoners beat their victim with a television set, Sveriges Television (SVT) reported.
According to prosecutors, the prisoners carried out their torture-like violence by trapping the victim in his cell for hours at a time.
As part of their scheme, the inmates stabbed their fellow prisoner on several occasions, using a range of items, including a scissors, a potato peeler, and a can opener.
They also cut the prisoner using a broken plate and a razor blade.
“It’s very unusual for such serious violence to take place here,” prison head Gert-Arne Sköld told the Expressen newspaper.
“On the other hand, it’s not uncommon at other Swedish prisons.”
On Tuesday, prosecutor Marianne Staaf formally charged four men and one woman, aged 27 to 47, with attempted aggravated robbery and being an accessory to blackmail.
According to the indictment, the woman’s involvement in the incident entailed her having delivered a threat to a third party over the phone.